Implantable electrical stimulation devices have been developed for therapeutic treatment of a wide variety of diseases and disorders. For example, implantable cardioverter defibrillators (ICDs) have been used in the treatment of various cardiac conditions. Spinal cord stimulators (SCS), or dorsal column stimulators (DCS), have been used in the treatment of chronic pain disorders including failed back syndrome, complex regional pain syndrome, and peripheral neuropathy. Peripheral nerve stimulation (PNS) systems have been used in the treatment of chronic pain syndromes and other diseases and disorders. Functional electrical stimulation (FES) systems have been used to restore some functionality to otherwise paralyzed extremities in spinal cord injury patients.
Typical implantable electrical stimulation systems can include a system with one or more programmable electrodes on a lead that are connected to an implantable pulse generator (IPG) that contains a power source and stimulation circuitry. However, these systems can be difficult and/or time consuming to implant, as the electrodes and the IPG are usually implanted in separate areas and therefore the lead must be tunneled through body tissue to connect the IPG to the electrodes. Also, leads are susceptible to mechanical damage over time as they are typically thin and long.
Recently, small implantable neural stimulator technology, i.e. microstimulators, having integral electrodes attached to the body of a stimulator has been developed to address the disadvantages described above. This technology allows the typical IPG, lead and electrodes described above to be replaced with a single device. Elimination of the lead has several advantages including reduction of surgery time by eliminating, for example, the need for implanting the electrodes and IPG in separate places, the need for a device pocket, tunneling to the electrode site, and strain relief ties on the lead itself. Reliability is therefore increased significantly, especially in soft tissue and across joints because active components, such as lead wires, are now part of the rigid structure and are not subject to the mechanical damage due to repeated bending or flexing over time.
However, the leadless integral devices tend to be larger and more massive than the electrode/lead assemblies, making it difficult to stably position the device in the proper position in respect to a nerve. Without device stability, the nerve and/or surrounding muscle or tissue can be damaged due to movement of the assembly.
There remains a need for a leadless integral device that is stably positioned on the nerve, and can provide for removal and/or replacement of the stimulation device with relative ease.